Geology topics

G. Edward Danielson

Publications and source records attributed to G. Edward Danielson.

4 recordsLinked to original sources

USGS1981

Encounter with Saturn: Voyager 1 imaging science results

As Voyager 1 flew through the Saturn system it returned photographs revealing many new and surprising characteristics of this complicated community of bodies. Saturn's atmosphere has numerous, low-contrast, discrete cloud features and a pattern of circulation significantly different from that of Jupiter. Titan is shrouded in a haze layer that varies in thickness and appearance. Among the icy satellites there is considerable variety in density, albedo, and surface morphology and substantial evidence for endogenic surface modification. Trends in density and crater characteristics are quite unlike those of the Galilean satellites. Small inner satellites, three of which were discovered in Voyager images, interact gravitationally with one another and with the ring particles in ways not observed elsewhere in the solar system. Saturn's broad A, B, and C rings contain hundreds of "ringlets," and in the densest portion of the B ring there are numerous nonaxisymmetric features. The narrow F ring has three components which, in at least one instance, are kinked and crisscrossed. Two rings are observed beyond the F ring, and material is seen between the C ring and the planet.

Science↗

USGS1974

Venus: Atmospheric motion and structure from Mariner 10 pictures

The Mariner 10 television cameras imaged the planet Venus in the visible and near ultraviolet for a period of 8 days at resolutions ranging from 100 meters to 130 kilometers. The general pattern of the atmospheric circulation in the upper tropospheric/lower stratospheric region is displayed in the pictures. Atmospheric flow is symmetrical between north and south hemispheres. The equatorial motions are zonal (east-west) at approximately 100 meters per second, consistent with the previously inferred 4-day retrograde rotation. Angular velocity increases with latitude. The subsolar region, and the region downwind from it, show evidence of large-scale convection that persists in spite of the main zonal motion. Dynamical interaction between the zonal motion and the relatively stationary region of convection is evidenced by bowlike waves.

Science↗

USGS1974

Mercury's surface: Preliminary description and interpretation from Mariner 10 pictures

The surface morphology and optical properties of Mercury resemble those of the moon in remarkable detail and record a very similar sequence of events. Chemical and mineralogical similarity of the outer layers of Mercury and the moon is implied; Mercury is probably a differentiated planet with a large iron-rich core. Differentiation is inferred to have occurred very early. No evidence of atmospheric modification of landforms has been found. Large-scale scarps and ridges unlike lunar or Martian features may reflect a unique period of planetary compression near the end of heavy bombardment by small planetesimals.

Science↗

USGS1971

Imaging of Mercury and Venus from a flyby

This paper describes the results of study of an imaging experiment planned for the 1973 Mariner Venus/Mercury flyby mission. Scientific objectives, mission constraints, analysis of alternative systems, and the rationale for final choice are presented. Severe financial constraints ruled out the best technical alternative for flyby imaging, a film/readout system, or even significant re-design of previous Mariner vidicon camera/tape recorder systems. The final selection was a vidicon camera quite similar to that used for Mariner Mars 1971, but with the capability of real time transmission during the Venus and Mercury flybys. Real time data return became possible through dramatic increase in the communications bandwidth at only modest sacrifice in the quality of the returned pictures. Two identical long focal length cameras (1500 mm) were selected and it will be possible to return several thousand pictures from both planets at resolutions ranging from equivalent to Earthbased to tenths of a kilometer at encounter. Systematic high resolution ultraviolet photography of Venus is planned after encounter in an attempt to understand the nature of the mysterious ultraviolet markings and their apparent 4- to 5-day rotation period. Full disk coverage in mosaics will produce pictures of both planets similar in quality to Earthbased telescopic pictures of the Moon. The increase of resolution, more than three orders of magnitude, will yield an exciting first look at two planets whose closeup appearance is unknown.

Icarus↗